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We present a compact model for the DC and small signal AC analysis of Organic Thin Film Transistors (OTFTs). The DC part of the model assumes that the electrical current injected in the OTFT is limited by the presence of a metal/organic semiconductor junction that, at source, acts as a reverse biased Schottky junction. By including this junction, modeled as a reverse biased gated diode at source, the DC model is able to reproduce the scaling of the electrical characteristics even for short channel devices. The small signal AC part of the model uses a transmission line approach in order to compute the impedances of the channel and parasitic regions of the device. The overlap capacitances and the presence of non-ideal metal/organic semiconductor junctions are taken in account as well and the model can be easily adapted to different device geometries. The model is particularly well suited for printed devices, often realized with large process tolerances, since it takes into consideration the presence of parasitic regions and their effect on the AC operation. The model has been validated on printed OTFTs using a pentace-derivative as organic semiconductor with a quite peculiar device layout. It has been fully implemented in Verilog-A programming language.

This work introduces a compact DC model developed for organic thin film transistors (OTFTs) and its SPICE implementation. The model relies on a modified version of the gradual channel approximation that takes into account the contact effects, occurring at nonohmic metal/organic semiconductor junctions, modeling them as reverse biased Schottky diodes. The model also comprises channel length modulation and scalability of drain current with respect to channel length. To show the suitability of the model, we used it to design an inverter and a ring oscillator circuit. Furthermore, an experimental validation of the OTFTs has been done at the level of the single device as well as with a discrete-component setup based on two OTFTs connected into an inverter configuration. The experimental tests were based on OTFTs that use small molecules in binder matrix as an active layer. The experimental data on the fabricated devices have been found in good agreement with SPICE simulation results, paving the way to the use of the model and the device for the design of OTFT-based integrated circuits.

We built a fiber-less prototype of an optical system with 156 channels each one consisting of an optode made of a silicon photomultiplier (SiPM) and a pair of light emitting diodes (LEDs) operating at 700 nm and 830 nm. The system uses functional near-infrared spectroscopy (fNIRS) and diffuse optical tomography (DOT) imaging of the cortical activity of the human brain at frequencies above 1 Hz. In this paper, we discuss testing and system optimization performed through measurements on a multi-layered optical phantom with mechanically movable parts that simulate near-infrared light scattering inhomogeneities. The baseline optical characteristics of the phantom are carefully characterized and compared to those of human tissues. Here we discuss several technical aspects of the system development, such as LED light output drift and its possible compensation, SiPM linearity, corrections of channel signal differences, and signal-to-noise ratio (SNR). We implement an imaging algorithm that investigates large phantom regions. Thanks to the use of SiPMs, very large source-to-detector distances are acquired with a high SNR and 2 Hz time resolution. The overall results demonstrate the high potentialities of a system based on SiPMs for fNIRS/DOT human brain imaging applications.

In this work, we investigate some major issues for the use of silicon photomultiplier (SiPM) devices in continuous wave functional near-infrared spectroscopy (CW fNIRS). We analyzed the after-pulsing effect, proposing the physical mechanism causing it, and determining its relevance for CW fNIRS. We studied the SiPM transients occurring as the SiPM device goes from the dark (LED in off state) to the illumination (LED in on state) conditions. and vice-versa. Finally, we studied the SiPM SNR in standard CW fNIRS operation. (C) 2018 Optical Society of America under the terms of the OS.A Open Access Publishing Agreement

Focusing on the interplay between interface chemistry, electrochemistry, and integrated electronics, we show a novel low-cost and flexible biosensing platform for continuous glucose monitoring. The amperometric biosensing system features a planar three-electrode structure on a plastic substrate, and a wireless near-field communication-powered electronic system performing sensor analog front-end, A/D conversion, digital control, and display tasks. The working electrode is made of electropolymerized poly (3,4-ethylenedioxythiophene) film onto a polyethylene terephthalate/gold electrode followed by immobilization of cross-linked glucose oxidase by glutaraldehyde. The advantages offered by such a device, including low-cost materials and instrumentation as well as the good sensitivity of 9.24 $\mu \text{A}/({\mathrm {mM}} \cdot {\mathrm {cm}}^{2})$ are promising tools for point-of-care monitoring. It is demonstrated that the devices are good candidates for the development of advanced sensing approaches based on the investigation of the noise produced during operation (fluctuation-enhanced sensing).

The poor results of traditional therapy in advanced carcinoid tumors and the well-proven uptake of 131I-MIBG shown by some of these tumors induced us to attempt a radiometabolic approach. We selected for the treatment 5 patients (3 men and 2 women) who showed progression of disease, a fairly good uptake of 131l-MIBG with severe related symptoms, and a poor response to traditional therapy. A cumulative radioactivity of 5.5-29.6 GBq was given. Acute side effects after 131l-MIBG ad ministration or late radiation-induced damages were not observed. Symptoms increased during the first 2-4 weeks in 2 patients: in one of these relief was achieved with drugs. Results concerning objective remission of the disease were unsatisfactory. In contrast, definite improvement of symptoms was shown in 2 of 5 patients, resulting in a better quality of life.